title: Pregnenolone protects the PC-12 cell line against amyloid beta peptide toxicity but its sulfate ester does not.
abstract: Pregnenolone (P), the main precursor of the steroids, and its sulfate ester, pregnenolone sulfate (PS), are the major neurosteroids produced in the neural tissue. Many neuroendocrinological studies stressed the neuroprotective role of neurosteroids although it has been suggested that the inhibition of P and PS synthesis can delay neuronal cell death. The potential roles of P and PS in vital neuronal functions and in amyloid beta peptide (Abeta) toxicity are not clearly identified. This work aims to investigate the effects of P and PS on cell viability and Abeta peptide toxicity in a concentration and exposure time-dependent manner in rat PC-12 cells. The cells were treated with 20muM Abeta peptide 25-35 and variable concentrations of P and PS ranging from 0.5muM to 100muM. To examine the effects of steroid treatment on Abeta peptide toxicity, 0.5muM (low) and 50muM (high) neurosteroids were used. The cell viability and lactate dehydrogenase release of cells were evaluated after 24, 48 and 72h. Morphological changes of cells were also examined. The treatment with higher than 1muM concentrations of P and PS significantly decreased the cell viability comparing to untreated cells. At lower concentrations, P and PS had no toxic actions until 72h. The Abeta treatment resulted in a significant decrease in cell viability comparing to untreated cells. P showed a dose-dependent protective effect against Abeta peptide in PC-12 cells. But its sulfate ester did not have the same effect on Abeta peptide toxicity, even it significantly decreased cell viability in Abeta-treated cells. Consequently, the discrepant effects of P and PS on Abeta peptide toxicity may provide insight on the pathogenesis of Alzheimer's disease.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Dokuz Eylul University, Mustafa Kemal Bulvard, Inciralti, 35340 Izmir, Turkey.
authors.forename: Pinar
authors.initials: P
authors.lastname: Akan
authors.forename: Servet
authors.initials: S
authors.lastname: Kizildag
authors.forename: Murat
authors.initials: M
authors.lastname: Ormen
authors.forename: Sermin
authors.initials: S
authors.lastname: Genc
authors.forename: Mehmet Ali
authors.initials: MA
authors.lastname: Oktem
authors.forename: Meral
authors.initials: M
authors.lastname: Fadiloglu
mesh_terms: D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008856:Microscopy, Fluorescence; D009596:Nitrophenols / Q000494:pharmacology; D016716:PC12 Cells; D010446:Peptide Fragments / Q000633:toxicity*; D011284:Pregnenolone / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D009596:Nitrophenols; D010446:Peptide Fragments; C018370:pregnenolone sulfate; C015802:2,6-dichloro-4-nitrophenol; D011284:Pregnenolone